Autoamtic choke means



Sept. 11, 1956 .1. e. ELSE AUTOMATIC CHOKE MEANS 2 SheetsSheet 1 Filed001;. 4, 1954 Sept. 11, 1956 J. G. ELSE 2,762,352

AUTOMATIC CHOKE MEANS Filed Oct. 4, 1954 2 Sheets-Sheet 2 INVENTORAUTOMATIC CHOKE MEANS John G. Else, Royal Oak, Mich., assignor toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareApplication ()ctober 4, 1954, Serial No. 460,008

13 Claims. (Cl. 123-119) The present invention relates to internalcombustion engines and more particularly to automatic choke meanstherefor.

When starting or operating a cold internal combustion engine, it isdesirable to increase the fuel-air mixture ratio. This may be easilyaccomplished by means of a choke valve disposed in the intake of thecarburetor. Since the required amount of choking will be a function ofthe engine temperature, the position of the choke valve may becontrolled by suitable thermostatic means responsive to the enginetemperature. The engine exhaust gases have been found to be a reliableindex to the engines temperature, and accordingly, it has been thepractice to heat the thermostatic element in the choke by means of airthat has passed through a stove which is in heat exchanging relationwith the engine exhaust gases. Although this has proved quite effective,considerable trouble has been experienced in transferring the correctamount of heat to the air for insuring proper operation of the chokevalve. As a result, the choke valve either opens before the engine hasbecome properly heated or the valve opens prematurely before the engineis adequately heated.

It is now proposed to provide a stove which is adapted to be disposed inheat exchanging relation with the engine exhaust gases for heating theair flowing to the thermostatic element in the automatic choke. Thestove may be formed integrally in the exhaust manifold so as to have oneside thereof open to the atmosphere. One or more fins may be provided inthe stove so as to form a tortuous path for increasing the amount ofheat transferred to the air in the stove. A cover may be secured to themanifold so as to cooperate with the fin to define one Wall of the path.In order to insure the temperature of the air in the stove being anaccurate function of the engine temperature, the cover may includethermal insulating means to prevent excessive heat losses to theatmosphere. In the present instance this means is provided by employinga cover which includes two members that are spaced from each other toform a dead air space therebetween. Thus as the air is drawn through thestove, it will be heated by the exhaust gases and when it passes thethermostat, it will cause the choke valve to be moved as a function ofthe engine temperature. By providing the insulating means the eifects ofthe atmospheric temperatures will be greatly reduced and the temperatureof the heated air will be a closer function of the engine temperature.

Fig. l is an end view of an engine employing the present invention.

Fig. 2 is a side view of the exhaust manifold taken substantially alongthe plane of line 22 in Fig. 1.

Fig. 3 is a cross sectional view taken substantially along the plane ofline 3-3 in Fig. 2.

Fig. 4 is a cross sectional view taken substantially along the plane ofline 44 in Fig. 2.

i Fig. 5 is a cross sectional view taken substantially along the planeof line 5-5 in Fig. 2.

nited States Patent 0 ice Fig. 6 is a perspective view of the cover forthe present stove with a portion thereof being broken away.

The present invention may be adapted for use on any suitable engine 10such as a V-type engine having a pair of angularly disposd banks ofcylinders 12 with an induction system 14 disposed therebetween. Theinduction system 14 may include a carburetor 16 which is mounted on anintake manifold 18 that has the opposite sides thereof abutting thecylinder heads 20. The manifold 18 may include one or more distributionpassages which are adapted to distribute the combustible charge of fueland air from the carburetor 16 to the various cylinders.

Exhaust manifolds 22 may extend along the opposite sides of the engine10 for collecting the exhaust gases from the cylinder combustionchambers and discharging them into the atmosphere. In the presentinstance the exhaust manifolds 22 include a plurality of exhaust ports24 that communicate with a chamber 26 for collecting the exhaust gasesfrom the engine 10. An outlet may be provided which communicates withthe chamber 26 for discharging the exhaust gases into an exhaust systemand/ or the atmosphere.

A choke valve 28 may be provided in the intake of the carburetor 16 formovement between the opened and closed positions to vary the air-fuelmixture ratio. Since the variations in the air-fuel mixture are afunction of the engines temperature, a thermostat 30 may be provided forcontrolling the valves 28 position. This thermostat 30 may be of anydesired form such as a bimetallic spring member and it may include ahousing on the side of the carburetor 16. In order to correlate thisthermostat 30 with the engine temperature, air may be heated by theengine exhaust gases and circulated through the housing of thethermostat. A stove 32 may be provided in the exhaust manifold 22 inheat exchanging relation with the hot exhaust gases flowing therethroughand a tube 34 may be provided which will interconnect the stove 32 withthe interior of the housing 30. Thus the interior of this housing willbe heated in proportion to the engine temperature.

The stove 32 may be formed in the exhaust manifold 22 as an integralpart of the casting, and it may include a cavity 35 that is formed inone wall of the manifold so as to have one side 36 thereof open to theatmosphere. A cover 38 may be secured to the manifold 22 to close thisopen side and form a chamber 40. An inlet 42 may be provided for air toenter this chamber 40from the atmosphere and an outlet 44 may beprovided in the manifold for allowing the tube 34 to interconnect thechamber 40 with the interior of the housing. Thus air may be drawn fromthe atmosphere and passed through the chamber 40, be heated by theexhaust gases and carried to the thermostat 30 to heat it. In order toincrease the amount of heat transferred to the air in the chamber 40,one or more fins 46 may be provided in the chamber 40 so as to extendout toward the cover 3S and cause the air to follow a tortuous path.Thus the inlet 42 may communicate with one end of the path with theoutlet 44 communicating with the other end.

The cover 38 may include an inner member 50 and an outer member 52 whichare preferably spaced from each other. The inlet 42 may be formed byregistering openings 48 in the cover 38. The inner member 50, in thepresent instance, is a plate positioned adjacent the fins 46 in thechamber 40. The outer member 52 of the cover 38 may be dished so as toproject outwardly from the inner member 50 and form a dead air space 54therebetween. This air space 54 will act as a very effective Thus whenthe engine is operating, the air will be drawn through the registeringopenings 48 into the tortuous path in the stove 32. Accordingly, the airtherein will be heated in proportion to the engine temperature. As theair is heated it may then flow from the outlet 44 into the tube 34 andinto the interior of the thermostatic housing 30. By properlyproportioning the path and the spacing between the inner and outermembers 50 and 52, respectively, forming the cover 38, the amount ofheat transferred to the air may be varied to provide the optimum amountof heat for thermostat 30. By increasing the spacing between the twocovers, the amount of insulation may be varied so that the effects ofatmospheric temperature variations will not aifect the temperature ofthe air flowing to the thermostat thus making the thermostat moreresponsive to engine tem perature.

It will thus be seen that a heat stove for an automatic choke has beenprovided which may easily be constructed to insure proper heating of thechoke so that it will be more nearly a function of the enginetemperature.

I claim:

1. Means for heating a thermostatic element in a choke comprising astove for heating the air flowing to said element, said stove having oneside thereof forming a portion of a wall of an exhaust manifold andbeing in direct heat exchanging relation with the engine exhaust gasesin said manifold, and an outlet in said stove adapted to receive meansfor interconnecting said stove with said thermostatic element.

2. A stove for a choke having thermal responsive means operativelyconnected thereto, said stove comprising a pocket projecting into anexhaust manifold to form at least a portion of one Wall thereof in heatexchanging relation with the exhaust gases inside of said manifold,another side of said pocket being open to the atmosphere, a coversecured to said manifold across said open side for closing said openside and thereby forming an air passage in heat exchanging relation withsaid exhaust gases and outlet means in said pocket communicating withsaid air passage and being adapted to be connected to said thermalresponsive means.

3. An exhaust manifold comprising a member having a chamber therein forcollecting exhaust gases discharged from an engine, a housing formedintegrally in one wall of said manifold to project into said chamber inheat exchanging relation with the exhaust gases therein, one side ofsaid housing being open to the atmosphere, a cover attached to saidmanifold to close said open side and form a tortuous path in saidhousing in heat exchanging relation with said exhaust gases, an inletinterconnecting said path in said housing with the atmosphere, and anoutlet communicating with said path in said housing and being adapted tobe connected to thermal responsive choke means.

4. An exhaust manifold comprising a member adapted to be secured to anengine, said member having a chamber therein for collecting the exhaustgases discharged fromsaid engine, a housing provided in one wall of saidmanifold to project into said chamber in heat exchanging relation withthe exhaust gases therein, one side of said housing being open to theatmosphere, a cover attached to said manifold to close said open side,at least one fin in said housing cooperating with said cover so as toform a tortuous path in heat exchanging relation with said exhaustgases, an inlet interconnecting one end of said path with theatmosphere, an outlet communicating with the opposite end of said pathand being adapted to be connected to thermal responsive choke means.

5. An exhaust manifold comprising a member adapted to be secured to anengine and having a chamber for collecting exhaust gases discharged fromsaid engine, a housing provided in one wall of said manifold with oneside thereof open to the atmosphere, a. cover attached to said manifoldfor closing said open side of said housing and forming a chamberdisposed in heat exchanging relation with said exhaust gases, said coverincluding means for thermally insulating said chamber from theatmosphere, an inlet interconnecting said chamber with the atmosphereand an outlet communicating with said chamber and being adapted tocommunicate with thermal responsive choke means.

6. An exhaust manifold comprising a member adapted to be secured to anengine and having a chamber therein for collecting the exhaust gasesdischarged from said engine, a housing provided in one wall of saidmanifold to project into said chamber in heat exchanging relation withthe exhaust gases therein, one side of said housing being open to theatmosphere, at least one fin positioned in said housing to define atortuous path in heat exchanging relation with said exhaust gases, acover attached to said manifold for closing said open side andcooperating With said fin to form one wall of said path, said coverincluding means for insulating the contents of said path from theatmosphere, an inlet interconnecting the atmosphere with one end of saidpath, and an outlet communicating with the opposite end of said path andbeing adapted to be connected to thermal responsive choke means.

7. An exhaust manifold comprising a member adapted to be secured to anengine and having a chamber therein for collecting the exhaust gasesdischarged from said engine, a housing provided in one wall of saidmanifold with one side thereof being open to the atmosphere, a coverattached to said manifold for closing said open side of said housing andforming a chamber disposed in heat exchanging relation with said exhaustgases, said cover including an inner member and an outer member disposedin spaced relation to each other to provide a dead air spacetherebetween for thermally insulating said chamber from the atmosphere,an inlet interconnecting said chamber with the atmosphere and an outletcommunicating with said chamber and being adapted to com municate withthermal responsive choke means.

8. An exhaust manifold comprising a member adapted to be secured to anengine and having a chamber therein for collecting the exhaust gasesdischarged from said engine, a housing provided in one wall of saidmanifold to project into said chamber in heat exchanging relationWiththe exhaust gases therein, one side of said housing being open tothe atmosphere, at least one fin positioned in said housing so as todefine a tortuous path in heat exchanging relation with said exhaustgases, an inner cover attached to said manifold so as to close said openside and cooperate with said fin to form one wall of said path, an outercover positioned on said inner cover and forming a dead air spacetherebetween for thermally insulating said path from the atmosphere, aninlet interconnecting the atmosphere with one end of said path, and anoutlet communicating with the opposite end of said path and beingadapted to be connected to an automatic choke.

9. In an engine having a carburetor with a thermal responsive chokethereon, the combination of an exhaust manifold for collecting theengine exhaust gases, a stove provided in said manifold to project intothe interior thereof and form a substantially plane wall in heatexchanging relation with said exhaust gases, one side of said stovebeing open to the atmosphere, a cover secured to said manifold forclosing said open side, an inlet interconnecting the interior of saidstove with the atmosphere and an outlet communicating with said interiorand with the thermal responsive means in said choke.

10. In an engine having a carburetor with a choke valve therein, thecombination of a thermostatic element disposed inside of a housing foractuating said choke valve, an exhaust manifold for collecting theexhaust gases from said engine, a stove formed integral with one wall ofsaid manifold to project into said exhaust gases in heat exchangingrelation therewith and having one side thereof open to the atmosphere,at least one fin positioned in said housing to form a tortuous path, acover secured to said manifold for closing said open side andcooperating with said fin to form one wall of said path, said coverincluding means for thermally insulating said path from the atmosphere,an inlet formed in said cover for interconnecting one wall of said pathwith the atmosphere, an outlet communicating with the other end of saidpath, and a passage interconnecting said outlet with the interior ofsaid housing for carrying heated air from said path to said thermostaticelement.

11. The combination of claim 10 wherein said cover includes an innermember and an outer member which are disposed in spaced relation witheach other to form a dead air space therebetween.

12. An exhaust manifold for an engine having a choke automaticallycontrolled by a thermostatic element, said exhaust manifold comprising amember having a chamber therein for collecting the exhaust gasesdischarged from said engine, a stove in one side of said member, oneside of said stove forming at least a portion of one wall of saidchamber and being in direct heat exchanging relation with the engineexhaust gases therein, an inlet for interconnecting said stove with theatmosphere and an outlet adapted for interconnecting said stove withsaid thermostatic element.

13. An exhaust manifold for an engine having a choke automaticallycontrolled by a thermostatic element, said manifold comprising a memberhaving a chamber therein for collecting the exhaust gases dischargedfrom said engine, a recessed pocket formed in said member with one sidethereof being open to the atmosphere, another side of said pocketforming a portion of one wall of said chamber and being in direct heatexchanging relation With the engine exhaust gases in said manifold, saidopen side of said pocket being adapted to be closed by a removable coversecured to said member to form an air path in heat exchanging relationwith said exhaust gases and having one end thereof adapted to open tothe atmosphere and the other end adapted to be connected to saidthermostatic element.

Boyce Aug. 26, 1952 Meinzinger et a1 Sept. 29, 1953

